The back taxes that Apple allegedly owes to Ireland will be paid into an escrow in the coming months, TDs and Senators have been told.

A senior official with the Department of Finance said the process of appointing a custodian agent is almost complete, and that an announcement of who it is will be made "very shortly".

John Hogan, assistant secretary in the tax division of the department, told the Public Accounts Committee that the process of securing investment managers will be completed next month.

"Our best guess is that all of that will facilitate the flow of funds into the account through the course of quarter two as early as possible, we hope and anticipate," Mr Hogan said.

One of his colleagues also confirmed that the cost of the process to date has been €2.5m.

That is unlikely to increase significantly, the committee heard. Niall Cody, the chairman of the Revenue Commissioners, said the amount of money due to be paid by Apple will be in and around the €13bn stated by the European Commission.

"It's in that ballpark," Mr Cody said.

He was responding to a question from Fianna Fáil TD Marc MacSharry about whether the bill his office is obliged to calculate will be in line with the record EU estimate, which both Dublin and Apple are appealing.

"Over 95pc of the calculations are completed and we have agreed with the [European] Commission that all our calculations will be with them before the end of April."

Mr Hogan also said there had been no expressions of interest from other member states towards the Apple money.

Responding to a question about resources from Independent TD Catherine Murphy, Mr Cody said staffing levels were 6,600 full-time equivalents, to 5,700 in 2014. Staff numbers are due to increase to 6,114 this year.